聚合物/甜菜碱表面活性剂提高水驱后残余油采收率研究

Enhanced residual oil recovery by using polymer/betaine surfactant system after water flooding

利用不加碱可形成超低界面张力的甜菜碱表面活性剂/聚丙烯酰胺二元复合体系,通过流变性实验,分析了甜菜碱表面活性剂对聚合物/表面活性剂二元复合体系流变性的影响;通过可视化的微观驱油实验和人造岩心驱油实验,分析了聚合物/表面活性剂二元体系的粘弹性和界面张力对采收率的影响,研究了该二元复合体系对水驱后残余油的作用机理。结果表明,实验用的两性表面活性剂体系与油可以达到超低界面张力,表面活性剂体系对无碱二元体系的粘弹性影响非常小。在驱替水驱残余油过程中,形成超低界面张力的甜菜碱表面活性剂/聚丙烯酰胺二元复合体系可以同时发挥活性剂的超低界面张力作用和聚合物溶液的粘弹性作用,使该二元体系的采收率高于单一的表面活性剂体系和聚合物驱油体系,并且该二元体系的粘弹性越大,采收率越高。界面张力由10-2mN/m降至10-3mN/m时的最终采收率均高于界面张力为10-2mN/m时增加聚合物溶液的质量浓度和相对分子质量两种情况下的最终采收率。

Using a polymer/betaine surfactant compound system for short surfactant/polymer （SP） compound system that can attain ultra-low interfacial tension with oil at conditions of no-alkali, the effect of betaine surfactant on the theology of SP compound system was analyzed through rheology experiment. Through oil-displacement experiments by micro-visualization models and artificial cores, the influence of visco-elasticity and interfacial tension of SP compound system on recovery efficiency was analyzed, and the action mechanism of the SP compound system on residual oil after water flooding was studied. The results show that the ultra-low interfacial tension between amphoteric betaine surfactant and oil can be formed, and the influence of betain surfactant on viscolasticity of the SP compound system is slight. Both the mobility control characteristic of polymer and the ultra-low interfacial tension characteristic of the surfactant can be utilized fully in polymer/amphoteric surfactant flooding. The core flooding experiments indicate that the oil recovery after polymer/surfactant systems flooding is better than that of single surfactant flooding and is also better than that of single polymer flooding, and the visco-elasticity of the SP compound system is larger, oil recovery is higher. When the interfacial tension decreases from 10^-2 mN/m to 10^-3 mN/m, the ultimate recovery of SP compound solution at 10^ -3 mN/m is higher than that of the increase in mass concentration or relative molecule mass of SP compound system at 10 ^-2 mN/m.